new to the forums and did a little research. probably will get flamed for this but i found a good deal on a synchronic bov and was wondering how it performs and how it would affect the car. i have a 2004 a4 of course and at the moment it is stock (just want to pick it up before he sells it). i read the newbie forums and it says that 2000+ audis have the sensors stock so it would be safe to run any bov as long as it stays closed during idle. but it also says that b6s can simply remove the maf and run any bov they want. i am a little confused. can anyone shed some light on it for me. i know there are a lot of bovs out there and they all work in somewhat the same way. i took a look at their site and this bov seams promising. anyone with experience? or can point me in the right direction for stats and the best way to install?

thanks in advance

 

I'm no expert, but my understanding has been that these cars need diverter valves rather than blow off valves. The reason for this is that the air has already been metered, so a BOV basically becomes equivalent to a really big intake leak, causing the ECU to think it's got more air coming in than it really does. This makes the air/fuel ratio too rich.

Of course, if you're removing the MAF, that might not occur, but I would think that this would somewhat handicap the ECU's ability to properly run the engine and potentially cause you all sorts of other problems. Does this make the car adjust fuel only based on the O2 sensors in the exhaust?

Again, I'm not an expert - hopefully someone with more knowledge can confirm or deny what I've said.

 

thanks for the quick reply. according to another post ( i cant find the link atm) says the newer particulary 2000 and up the maf will compensate for the lack of air meaning you will only run rich for a day or two. the synchronic bov according to the site has a recirculator meaning it should run like a dv? will i have the bov sound? the piston in there is supposedly the fastest on the market or so they say increasing throttle response.

 

If it recirculates the air back into the system, then it basically is a DV rather than a BOV, so you wouldn't run rich and you wouldn't get the sound. That "chirping" sound happens when a BOV vents to atmosphere.

As far as upgraded DVs that are known to be good with these cars go, I've seen both the APR R1 and the Forge 007 valves recommended. The R1 is a diaphragm valve like the stock one, but made with stronger materials - supposedly it doesn't need servicing over its lifetime. The 007 is a piston-based valve, meaning it probably lasts longer, but needs to be taken apart to be oiled and possibly to have its o-rings/gaskets replaced occasionally (I think like once a year or every two years or something).

 

i'm thinking of buying one myself for by b6. but i'm trying to get more info about them..

 

heard a lot of good things. apparently there is a changable valve that lets you recirculate or vent into atmosphere.

 

Yeah, I read their site and it looks like it's configurable either way, though it appears you have to buy an extra kit to recirculate. Seems like it ought to work fine, and the advertising text sure sounds good - I'd be curious to know what anyone who's actually got one's experience has been.